Electrohydraulic Control for Farm Vehicles

Input/output modules that are combined with any of the electronic controllers via CANbus communication extend the total input/output capacity of systems by eight to 16 I/O, depending on the module added. The modules can also be located remotely from the controller, providing additional application flexibility.

The Eaton 72400 is a servo-controlled, variable-displacement, piston-type pump displacing 2.48 in3/rev (40.6 cm3/rev) and operating at 3,500 psi (241 bar). At an average input speed of 1,900 rpm it produces 20 gpm (76 lpm) of flow to the front wheel motors.

The single hydrostatic pump is able to control both front wheels by using an FDC3 positraction flow divider cartridge. This valve allows for distribution of the pump flow with enough differential to make the tight turns required when spraying around obstacles or turning at the end of the field.

The auxiliary pump's primary output operates the fluid delivery pump for the sprayer. Excess fluid from the EFV2 is directed to a seven-section directional valve that operates the boom functions on the sprayer. The front-wheel-assist system is activated by a three-position switch in the cab that also selects the high- or low-speed operating range. Once engaged, system operation is completely automatic and transparent to the operator. "The hydraulic front-wheel-assist system works so well, I've been using it in dry field conditions, too," Bossuyt said. "I've noticed that with power to the front wheels, the engine is running cooler and doesn't seem to be working as hard."

The whole project took eight months to 10 months from start to finish. HyPower delivered the controller, pumps, valves, hose assemblies, and some other components as needed. All of the fabrication was completed in the farm workshop.

Given the concerns about weight and sinking into the mud, I was surprised with the relatively thin tires. Being in the mining industry for a number of years, the first thing that was done when needing "high flotation" was to increase the width of the tracks in that case. I wonder why a wider tire wasn't implemented here - or is that a farming requirement due to the width of the furrows?

Chuck, the silo story is another impressive story about hydraulics used on the farm. Are these issolated instances of inventive solutions -- or, do some of these solutions get commercialized. I would guess the need goes beyond these individual instances.

A spray rig needs to be able to make extremely tight turns at the end of the field. Any normal steering axle that is also driven would be limited by the angle of the wheels because of the universal joints. Some 4 wheel drive tractors use a right angle drive at the top of the steering kingpin through a hollow kingpin down to the wheel. Problem for an application like this with extremely low production would be that the cost of machining and fabrication of the special gears and such would be prohibitive.

The rear wheels can be driven by a set of gears, or belts, or chains without a problem, but the ability to turn makes the front axle more difficult.

Don't know if you have ever spent any time on any farm equiptment, but it is normal that ag equiptment is able to have a turn radius that is little longer than the length of the vehicle. A normal 4 wheel drive truck has a turning radius larger than a comparable 2 wheel drive truck. And most 4 wheel drive axles, when engaged, require an even larger turn radius.

Consider that a field will have rows spaced 30"(or 24"). The wheels may be spaced at 120" to go down the center of the rows. That puts 4(or 5) rows under the tractor. There will be 3 rows outboard on each side. So I get to the end of the row and pick up the implement at the end of the row and as soon as it is clear of the crop I do a hard turn to clear the fence at the edge of the field (and I don't allow any extra rom because if I make the turn around area 4 foot bigger I lose a couple acres at each end of the field) and then I make a sharp turn into the sixth row over and head to the other end of the field. If I have to wrestle with a vehicle with a large turn radius I will waste a lot of time trying to get out of the currrent row and into the next. With 3500 acres to work I don't have a lot of time to spend maneuvering, as getting the current spray on the field may be a time sensitive operation.

The picture shows "crop clearance" for the rear wheels, but the article states "The normal transmission output is used to drive the rear wheels." I'm used to seeing a traditional differential rear end, but I obviously dont' see a "pumpkin" hanging down low.

Did they install some sort of bevel gear adapters on the end of the normal differential, with an equivalent set down on the wheel centers?

I agree it's impressive, Rob. The ag industry is known for innovative use of hydraulics and this is a perfect example. A few years ago (okay, maybe it was 25 years ago), I did a story for Design News about a farmer who developed an electrohyadulic actuation system to tip over a silo, lay it on its side, and lift it onto a flat bed trailer.

This is quite an impressive makeover. I would guess there are plenty of situations where this electrohydraulic vehicle would solve problems on farms. I wonder if these folks are planning to commercialize their vehicle.

It won't be too much longer and hardware design, as we used to know it, will be remembered alongside the slide rule and the Karnaugh map. You will need to move beyond those familiar bits and bytes into the new world of software centric design.

People who want to take advantage of solar energy in their homes no longer need to install a bolt-on solar-panel system atop their houses -- they can integrate solar-energy-harvesting shingles directing into an existing or new roof instead.

Kaspersky Labs indicated at its February meeting that cyber attacks are far more sophisticated than previous thought. It turns out even air-gapping (disconnecting computers from the Internet to protect against cyber intrusion) isn’t a foolproof way to avoid getting hacked. And Kaspersky implied the NSA is the smartest attacker.

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